http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50713
Bug #: 50713
Summary: SLP vs loop: code generated differs
Classification: Unclassified
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: vincenzo.innoce...@cern.ch
in the following code
for "float"
the code generated by "dosum" and "dosuml" differs (dosum better)
for "complex"
"sum" does not vectorize! (a problem in itself)
"dosum" excellent vectorization, dusuml: same issue that with floats
if you have time please have a look of what happens with aligned(32)
sse vs avx, float vs double… (not an urgent use case at the moment)
compiled with
c++ -Ofast -ftree-vectorizer-verbose=2 -c slp2.cc -mtune=corei7 -msse4.2
// typedef __complex__ float Value;
typedef float Value;
// typedef double Value;
struct A {
Value a[4];
} __attribute__ ((aligned(16)));
A a1, a2, a3;
A sum(A a, A b) {
a.a[0]+=b.a[0];
a.a[1]+=b.a[1];
a.a[2]+=b.a[2];
a.a[3]+=b.a[3];
return a;
}
A suml(A a, A b) {
for (int i=0;i!=4;++i) a.a[i]+=b.a[i];
return a;
}
void dosum() {
a1 = sum(a2,a3);
}
void dosuml() {
a1 = suml(a2,a3);
}
float
========
sum(A, A):
movq %xmm2,0xc8(%rsp)
movq %xmm3,0xd0(%rsp)
movq %xmm0,0xd8(%rsp)
movaps 0xc8(%rsp),%xmm0
movq %xmm1,0xe0(%rsp)
addps 0xd8(%rsp),%xmm0
movaps %xmm0,0xa8(%rsp)
movq 0xa8(%rsp),%rax
movaps %xmm0,0xe8(%rsp)
movq 0xf0(%rsp),%xmm1
movd %rax,%xmm0
ret
nopl (%rax)
suml(A, A):
movq %xmm2,0xc8(%rsp)
movq %xmm3,0xd0(%rsp)
movq %xmm0,0xd8(%rsp)
movaps 0xc8(%rsp),%xmm0
movq %xmm1,0xe0(%rsp)
addps 0xd8(%rsp),%xmm0
movaps %xmm0,0xa8(%rsp)
movq 0xa8(%rsp),%rax
movaps %xmm0,0xd8(%rsp)
movq 0xe0(%rsp),%xmm1
movd %rax,%xmm0
ret
nopl (%rax)
dosum():
movaps _a2(%rip),%xmm0
addps _a3(%rip),%xmm0
movaps %xmm0,_a1(%rip)
ret
nopw %cs:sum(A, A)(%rax,%rax)
dosuml():
movq _a2(%rip),%rax
movq %rax,0xb8(%rsp)
movq _a2+0x00000008(%rip),%rax
movq %rax,0xc0(%rsp)
movq _a3(%rip),%rax
movq %rax,0xc8(%rsp)
movq _a3+0x00000008(%rip),%rax
movq %rax,0xd0(%rsp)
movaps 0xc8(%rsp),%xmm0
addps 0xb8(%rsp),%xmm0
movaps %xmm0,0xa8(%rsp)
movq 0xa8(%rsp),%rax
movaps %xmm0,0xb8(%rsp)
movq %rax,_a1(%rip)
movq 0xc0(%rsp),%rax
movq %rax,_a1+0x00000008(%rip)
ret
complex
==========
sum(A, A):
movss 0x28(%rsp),%xmm7
movq %rdi,%rax
movss 0x2c(%rsp),%xmm6
movss 0x30(%rsp),%xmm5
movss 0x34(%rsp),%xmm4
movss 0x38(%rsp),%xmm3
movss 0x3c(%rsp),%xmm2
movss 0x40(%rsp),%xmm1
movss 0x44(%rsp),%xmm0
addss 0x08(%rsp),%xmm7
addss 0x0c(%rsp),%xmm6
addss 0x10(%rsp),%xmm5
addss 0x14(%rsp),%xmm4
movss %xmm7,(%rdi)
addss 0x18(%rsp),%xmm3
movss %xmm6,0x04(%rdi)
addss 0x1c(%rsp),%xmm2
movss %xmm5,0x08(%rdi)
addss 0x20(%rsp),%xmm1
movss %xmm4,0x0c(%rdi)
addss 0x24(%rsp),%xmm0
movss %xmm3,0x10(%rdi)
movss %xmm2,0x14(%rdi)
movss %xmm1,0x18(%rdi)
movss %xmm0,0x1c(%rdi)
ret
nopl sum(A, A)(%rax,%rax)
suml(A, A):
movaps 0x08(%rsp),%xmm0
movq %rdi,%rax
addps 0x28(%rsp),%xmm0
movaps %xmm0,0xe8(%rsp)
movaps %xmm0,0x08(%rsp)
movaps 0x18(%rsp),%xmm0
movq 0xe8(%rsp),%rcx
addps 0x38(%rsp),%xmm0
movaps %xmm0,0xe8(%rsp)
movq 0xe8(%rsp),%rdx
movaps %xmm0,0x18(%rsp)
movq %rcx,(%rdi)
movq 0x10(%rsp),%rcx
movq %rdx,0x10(%rdi)
movq 0x20(%rsp),%rdx
movq %rcx,0x08(%rdi)
movq %rdx,0x18(%rdi)
ret
nop
dosum():
movaps _a2+0x00000010(%rip),%xmm0
movaps _a2(%rip),%xmm1
addps _a3+0x00000010(%rip),%xmm0
addps _a3(%rip),%xmm1
movaps %xmm0,_a1+0x00000010(%rip)
movaps %xmm1,_a1(%rip)
ret
nopl sum(A, A)(%rax,%rax)
dosuml():
movq _a2(%rip),%rax
movq %rax,0x98(%rsp)
movq _a2+0x00000008(%rip),%rax
movq %rax,0xa0(%rsp)
movq _a2+0x00000010(%rip),%rax
movq %rax,0xa8(%rsp)
movq _a2+0x00000018(%rip),%rax
movq %rax,0xb0(%rsp)
movq _a3(%rip),%rax
movq %rax,0xb8(%rsp)
movq _a3+0x00000008(%rip),%rax
movq %rax,0xc0(%rsp)
movq _a3+0x00000010(%rip),%rax
movaps 0xb8(%rsp),%xmm0
addps 0x98(%rsp),%xmm0
movq %rax,0xc8(%rsp)
movq _a3+0x00000018(%rip),%rax
movaps %xmm0,0x88(%rsp)
movaps %xmm0,0x98(%rsp)
movaps 0xa8(%rsp),%xmm0
movq %rax,0xd0(%rsp)
movq 0x88(%rsp),%rdx
addps 0xc8(%rsp),%xmm0
movaps %xmm0,0x88(%rsp)
movq 0x88(%rsp),%rax
movaps %xmm0,0xa8(%rsp)
movq %rdx,_a1(%rip)
movq 0xa0(%rsp),%rdx
movq %rax,_a1+0x00000010(%rip)
movq 0xb0(%rsp),%rax
movq %rdx,_a1+0x00000008(%rip)
movq %rax,_a1+0x00000018(%rip)
ret
